JP4073808B2 - Network restructuring method, node, network restructuring program, and computer-readable storage medium storing the program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication network, and in particular, a network reconstruction method, a node, a link destination change method, a network rebuild program, and a link destination change program related to a communication network having a one-to-many communication form such as Bluetooth (registered trademark). And a storage medium on which the program is recorded.
[0002]
[Prior art]
Conventionally, devices having communication functions (hereinafter referred to as “terminals”) such as personal portable information terminals (hereinafter referred to as “PDA”), notebook personal computers, mobile phones and the like are mutually connected. In the case of communication to the Internet, wired communication via a cable such as RS-232C or USB (Universal Serial Bus) has been mainstream.
[0003]
On the other hand, near-field wireless communication technology has recently been proposed in which communication between devices is performed wirelessly. Representative short-range wireless communication technologies include IEEE 802.11, IEEE 802.15, and Bluetooth (registered trademark).
[0004]
When a communication network (hereinafter simply referred to as “network”) is constructed using such short-range wireless communication technology, a terminal that plays a role of maintaining synchronization on the network is required. These terminals are generally called a master, a coordinator, or the like, and are hereinafter referred to as “master terminals”.
[0005]
The master terminal needs to be appropriately selected in consideration of restrictions due to the reach of radio waves. FIG. 18 shows a difficult example of building a wireless network due to the radio wave arrival distance. When terminals A to D are arranged as shown in FIG. 5A, if terminal A is a master terminal, radio waves from terminal A do not reach terminal D, so terminal D cannot participate in the network. .
[0006]
On the other hand, as shown in FIG. 18B, when terminal B is a master terminal, radio waves from terminal B reach all other terminals A, C, and D, so that all terminals A to D enter the network. Can participate. Thus, if the user does not grasp the positional relationship of all terminals, an appropriate terminal cannot be selected as the master terminal.
[0007]
In addition, the master terminal needs to be appropriately selected in consideration of the adverse effects caused by obstacles. FIG. 19 shows a difficult example of building a wireless network caused by an obstacle. When terminals A to D are arranged as shown in FIG. 5A and an obstacle is arranged between terminals B and D, if terminal B is a master terminal, the radio wave from terminal B The terminal D cannot join the network because it does not reach the terminal D due to an object.
[0008]
On the other hand, as shown in FIG. 19B, if the terminal C is a master terminal, the radio waves from the terminal C reach all other terminals A, B, and D, so that all the terminals A to D enter the network. Can participate. Thus, if the user does not grasp the relationship between terminals that cannot perform wireless communication due to obstacles, an appropriate terminal cannot be selected as the master terminal.
[0009]
Further, when the terminal is a mobile device such as a mobile phone or a PDA, it is assumed that the position is constantly changed, and it is difficult for the user to select the master terminal accurately.
[0010]
With respect to this problem, in the “master leaving network operation method” described in Patent Document 1 below, when a network is constructed between a plurality of communication devices using Bluetooth (registered trademark), A method is disclosed in which a network can be operated by a backup master when an operating communication device cannot play its role.
[0011]
In this method, connection information is transmitted from at least one slave among a plurality of slaves existing in the network, and when the network master is disconnected, the method is used as a backup master based on the transmitted connection information. Determining a priority of at least one of the plurality of slaves, and broadcasting the determined priority of the backup master to at least one other slave of the plurality of slaves.
[0012]
According to this method, when the network master is disconnected, an appropriate backup master can be selected based on the connection information, and the network can be operated by the selected backup master.
[0013]
[Patent Document 1]
JP 2002-1111689 A (published on April 12, 2002)
[0014]
[Patent Document 2]
JP 2002-232433 A (released on August 16, 2002)
[0015]
[Problems to be solved by the invention]
However, the communication method disclosed in Patent Document 1 can be applied only when the master leaves. Further, for example, in an environment where a plurality of networks having a one-to-many connection form are connected, an appropriate backup master cannot be selected, and the network cannot be properly constructed. This complicates the network structure and increases the power consumption of the entire network due to the waste of the master terminal in the network, and the communication speed resulting from the increase in retransmission processing that occurs because packet collisions easily occur. It was causing problems such as reduction.
[0016]
The present invention has been made in order to solve the above-described problems, and its object is to suppress an increase in power consumption and a reduction in communication speed in the entire network due to a complicated network structure. It is to provide a network restructuring method, a node, a wireless link destination changing method, and the like.
[0017]
[Means for Solving the Problems]
In order to solve the above-described problem, the network restructuring method of the present invention has one or more nodes operating in the slave mode (hereinafter referred to as “master node”) for the node operating in the master mode (hereinafter referred to as “master node”). Hereinafter, it is a network restructuring method for reconstructing a network including a plurality of small networks linked to each other by a detecting step for detecting nodes to which each node can be linked, A creation step for creating detection information including a detection result of the node; a selection step for selecting the master node using the detection information created by the creation step so as to reduce the number of the master nodes; And a construction step for constructing a small network including the nodes selected by the steps. There.
[0018]
According to the above method, from the detection information created in the creation step, it is determined which node can be linked to each node included in the network. Thereby, since the topology of the network can be changed variously, the network topology can be changed so that the number of master nodes is reduced. In this case, since the number of master nodes is reduced, an increase in power consumption in the entire network and a reduction in communication speed can be suppressed.
[0019]
The selection step includes a first search step for searching for one node to which all the nodes can be linked, and if no corresponding node can be found in the first search step, all the nodes are included in the combination of the nodes. A combination of the nodes that can be linked to the node, a second search step of searching for a node that can be linked to at least two nodes in the combination of the nodes, and a node that corresponds in the second search step Cannot be found, increase the number of nodes in the combination of the nodes and repeat the second search step, and the corresponding node in the first search step or the corresponding node in the second search step. And a determination step of determining a combination as the master node.
[0020]
In this case, it is checked whether the network can be constructed while increasing the number of master nodes in order from 1. Therefore, since the number of master nodes that can construct a network can be minimized, an increase in power consumption in the entire network and a reduction in communication speed can be minimized.
[0021]
Furthermore, the network restructuring method of the present invention is characterized in that, in the above method, the construction step includes a notification step of notifying other nodes that the node is switching the link destination.
[0022]
According to the above method, another node can know that a certain node is switching the link destination. Thereby, it is possible to prevent data loss due to data being transmitted to the node being switched by stopping transmission to the node being switched or changing the routing information.
[0023]
The node of the present invention is a node capable of constructing a small network in which one or more slave nodes are linked to the master node, and can operate in either the master mode or the slave mode. A detection means including a detection means for detecting a linkable node, a detection result of the own node obtained by the detection means, and a detection result of each node constituting a network including a plurality of the small networks. A storage unit that stores information, a communication unit that communicates the detection information with the outside, and a master selection that performs selection of the master node so that the number of the master nodes in the network is reduced using the detection information And a mode of the own node and a link destination node are selected based on the selection of the master selection means and the master selection means. It is characterized in that it comprises a construction means for constructing a small network with.
[0024]
According to said structure, it becomes clear from the detection information memorize | stored in the memory | storage means to which node each node contained in a network can link. Thereby, since the topology of the network can be changed variously, the network topology can be changed so that the number of master nodes is reduced. In this case, since the number of master nodes is reduced, an increase in power consumption in the entire network and a reduction in communication speed can be suppressed.
[0025]
The master selection means includes a first search means for searching for one node to which all the nodes can be linked, and if the corresponding node cannot be found by the first search means, all the nodes are included in the combination of the nodes. Corresponding in a second search means for searching for a combination of the nodes that can be linked to any one of the nodes, a node that can be linked to at least two nodes in the combination of the nodes, and a second search means If the node to be found cannot be found, it repeats the second search means by increasing the number of nodes in the combination of the nodes, and the corresponding node in the first search means, or the corresponding in the second search means A determining unit that determines a combination of nodes as the master node may be provided.
[0026]
In this case, it is checked whether the network can be constructed while increasing the number of master nodes in order from 1. Therefore, since the number of master nodes that can construct a network can be minimized, an increase in power consumption in the entire network and a reduction in communication speed can be minimized.
[0027]
When other nodes have the same configuration, the master node determined by the determination unit is common to each node. Therefore, it is not necessary to provide a special node for determining the master node and changing the network topology.
[0028]
Furthermore, the node according to the present invention is characterized in that, in the above-described configuration, the construction means includes a notification means for notifying the execution of a switching process for linking with a selected link destination node.
[0029]
According to the above configuration, execution of link destination switching processing can be notified to other nodes. As a result, other nodes can prevent data loss due to data being transmitted to the local node during the switching process by stopping transmission to the local node or changing the routing information. it can.
[0030]
Further, the link destination changing method of the present invention is a node capable of constructing a small network in which one or more slave nodes are linked to the master node. A link destination changing method for changing a link destination in a node that can also operate, wherein a detection step for detecting a linkable node, and a node constituting a network including a plurality of the small networks acquired by the detection step A reception step of receiving detection information including a detection result of the node from the outside, an update step of updating the received detection information with a detection result of the own node acquired by the detection step, and a detection updated by the update step A transmission step of transmitting information to the outside, and a detection updated by the updating step Information is used to select the master node based on the first selection step for selecting the master node and the selection of the first selection step so that the number of the master nodes in the network decreases. And a second selection step for selecting a link destination node, and a switching step for switching the link destination when the link destination selected by the second selection step is different from the current link destination. It is a feature.
[0031]
According to the above method, from the detection information updated in the updating step, it is determined which node can be linked to each node included in the network. Thereby, since the topology of the network can be changed variously, the network topology can be changed so that the number of master nodes is reduced. In this case, since the number of master nodes is reduced, an increase in power consumption in the entire network and a reduction in communication speed can be suppressed.
[0032]
It should be noted that each step in the network reconstruction method can be executed on a computer by a network reconstruction program. Similarly, each step in the link destination changing method can be executed on a computer by a link destination changing program.
[0033]
Furthermore, the network reconstruction program or the link destination change program can be executed on an arbitrary computer by storing the network reconstruction program or the link destination change program in a computer-readable recording medium.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be applied to an arbitrary device such as a communication device or a communication system constituting a network having a one-to-many connection form. Hereinafter, as an example, a terminal according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, a terminal that performs communication in the master mode is referred to as a “master terminal”, and a terminal that performs communication in the slave mode is referred to as a “slave terminal”.
[0035]
FIG. 1A shows an example of a network in which a plurality of small networks having a one-to-many connection form are connected. In FIGS. 3A to 3C, the master terminal is indicated by “M”, the slave terminal is indicated by “S”, and the relay terminal described later is indicated by “R”.
[0036]
A solid line between the terminals indicates a state in which a master-slave wireless link is established. A broken line between terminals indicates a state in which a wireless link is possible but a terminal is not a wireless link due to reasons such that the terminals are slaves or do not participate in the network.
[0037]
In FIG. 2A, a network in which the master is the terminal 1 and the slave is the terminals 2 and 3 and a network in which the master is the terminal 4 and the slave is the terminals 5 and 6 are constructed. Here, the terminal 3 plays a role of bridging two networks by wirelessly linking with both of the two master terminals 1 and 4. Hereinafter, such a terminal serving as a bridge is referred to as a “relay terminal”.
[0038]
In Bluetooth (registered trademark), the slave terminal S can perform a radio link only to one master terminal M, and cannot perform a radio link to two or more master terminals M. In this case, the relay terminal R switches the processing so that the radio link is established to one master terminal M at a certain time and the radio link is established to the other master terminal M at another time at a certain time. Therefore, it can serve as a bridge between the two networks.
[0039]
In the environment of FIG. 1A, when a new terminal 7 joins the network, when the new terminal 7 cannot form a wireless link with the existing master terminals 1 and 4, it is shown in FIG. 1B. Thus, the new terminal 7 becomes the master terminal M, and the terminal 6 that performs a radio link to the new terminal 7 becomes the relay terminal. Thus, the number of master terminals M increases and the number of relay terminals R also increases.
[0040]
In the present invention, the network topology is changed so that the number of master terminals M is reduced as shown in FIG. 1C in the state shown in FIG. Thereby, an increase in power consumption in the entire network and a reduction in communication speed can be suppressed.
[0041]
[Embodiment 1]
One embodiment of the present invention is described below with reference to FIGS. FIG. 2 shows the internal configuration of the terminal 10 constituting the network of this embodiment. As shown in the figure, the terminal 10 includes a communication unit 11 that communicates with another terminal 10, a detection unit 12 that detects a communicable terminal, and detection information acquired from the communication unit 11 and the detection unit 12. The storage unit 13 stores the information, the control unit 14 that controls each unit, and the notification unit 15 that performs notification to the outside.
[0042]
FIG. 3 shows transition of the operation state of the terminal 10 shown in FIG. As shown in FIG. 3, the operating state of the terminal 10 is any one of an idle state (a), a detection information reception state (b), a periodic detection state (c), and a detection information transmission state (d). Note that when the operation of the terminal 10 starts, the idle state is entered.
[0043]
Next, processing performed in each operation state will be described with reference to FIGS. In the flowcharts shown in FIGS. 4 to 7, when transitioning to another operation state, the lower case alphabets a to d described together with the names of the operation states are used.
[0044]
First, the process in the idle state (a) will be described with reference to FIG. First, it is determined whether or not the communication unit 11 has received detection information from the partner terminal 10 (step S10. Hereinafter, it may be simply referred to as “S10”. The same applies to other steps). . When the detection information is received, the state transits to the detection information reception state (b).
[0045]
On the other hand, if no detection information has been received, whether or not a predetermined period (hereinafter referred to as “periodic detection period”) has elapsed since the transition to the idle state was made by a timer built in the control unit 14. Is determined (S11). If it has elapsed, the state transits to the periodic detection state (c). On the other hand, if it has not elapsed, the process returns to step S10 and the above operation is repeated.
[0046]
Here, the detection information is information as shown in FIG. 17, for example, the detection target terminal, whether or not the detection process has been performed, the connected partner terminal, and the network participating in the network. Information indicating whether the terminal is compatible with both the master mode and the slave mode. The detection result of terminal D does not exist because terminal D has not yet joined the network.
[0047]
The periodic detection period is a period set for performing detection processing at a certain interval. For example, if it is set to 3 minutes, the terminal periodically detects a terminal that can communicate at intervals of 3 minutes. Will be done. The periodic detection period may be specific to the terminal or may be set freely by the user. In addition, there may be a method in which an optimum periodic detection period is held in a terminal as a table and automatically adjusted according to the place and situation.
[0048]
Furthermore, the periodic detection period does not need to be a constant value. For example, the periodic detection period is set to have a minimum width of 3 minutes and a maximum width of 10 minutes. Further, the periodic detection period may be changed every time within the set range, such as the third time after 8 minutes and the fourth time after 5 minutes.
[0049]
If zero is set for the periodic detection period, the detection process is always performed, and if an infinite value or an implementation value that means it is set, the periodic detection process is temporarily stopped. You may do it. Here, the value on the implementation meaning infinity is, for example, a range in which the periodical detection period can be set in the program is 0 to 65535, and “65535” is regarded as infinity instead of an actual value. In this case, “65535” in the case where it is designed.
[0050]
Next, processing in the detection information reception state (b) will be described with reference to FIG. First, the control unit 14 compares the content of the received detection information with the detection information stored in the storage unit 13 (S20). If the content is the same (YES in S21), the idle state (a) Transition to. On the other hand, if the contents are different (NO in S21), the contents of the detection information stored in the storage unit 13 are updated so as to match the contents of the received detection information (S22).
[0051]
After step S22, the control unit 14 calculates an optimal solution for network construction from the updated detection information (S23). The contents of step S23 will be described later. Next, it is determined from the calculation result of the optimum solution whether or not the communication destination needs to be switched (S24). If it is determined that switching is not necessary (NO in S24), the state transitions to the idle state (a).
[0052]
On the other hand, if it is determined that switching is required (YES in S24), first, the notification unit 15 notifies the outside that the communication destination switching process is started (S25). Thereafter, the communication unit 11 performs communication destination switching processing (S26).
[0053]
In response to the result of the switching process, the notification unit 15 notifies the result of the switching process to the outside (S27), and the storage unit 13 updates the contents of the stored detection information (S28). In addition, about the content update process in step S28, for example, the difference between the conventional information and the new information is taken and overwritten with the new information. Thereafter, the state transits to the detection information transmission state (d).
[0054]
Here, in step S23, the calculation of the optimal solution for network construction from the detection information by the control unit 14 refers to determining a configuration in which the number of master terminals participating in the network decreases. An example of the determination process will be described with reference to FIGS.
[0055]
In the case of the network having the configuration shown in FIG. 8, the terminals exchange the detection results so that all the terminals A to F participating in the wireless network have the detection information table as shown in FIG. Become. Based on this detection information, when any one or a plurality of terminals become master terminals, it is checked whether all terminals can participate in the network.
[0056]
That is, assuming that one master terminal is used as a master terminal, first, a terminal that can participate in the network, that is, a terminal that can be wirelessly linked to the master terminal is investigated, and this is repeated for each terminal. . As a result, a table as shown in FIG. Note that the circles shown in FIG. 5A indicate that the terminal shown on the upper side is a terminal that can join the network when the terminal shown on the left side is the master terminal.
[0057]
Referring to FIG. 5A, it is understood that there is no solution that allows all the terminals to participate in the network when one master terminal is assumed.
[0058]
Therefore, consider the case where two master terminals are assumed. In this case, basically, as shown in FIG. 10A, a table assuming one master terminal may be superimposed. Thereby, a table as shown in FIG. 10B is acquired.
[0059]
For example, when two terminals A and B are set as master terminals, the terminals that can participate in the network are shown in FIG. 10A. The result when the terminal A1 is set as a master terminal and the terminal B1 are set as What is necessary is just to add the result at the time of setting it as a master terminal.
[0060]
Note that the circles shown in FIG. 10B have the same meaning as in FIG. 10B indicates that the terminal can participate in the network regardless of which of the two terminals on the left side is the master terminal. Such a terminal can be a relay terminal capable of bridging data between a network group having one terminal on the left as a master terminal and a network group having the other terminal as a master terminal. . When there are a plurality of master terminals, it should be noted that not all terminals participate in the network without such a terminal serving as a bridge.
[0061]
Thus, referring to FIG. 10 (b), looking at each combination when there are two master terminals, if terminals B and E are master terminals, all terminals participate in the network. I understand that I can do it. Referring to FIG. 2B, in each combination of the terminal A / E, the terminal B / F, and the terminal D / E, the terminals A to E are all circled, but the double circle Since there is no terminal with a mark, that is, a terminal to be a relay terminal, all terminals A to F do not participate in the network.
[0062]
As described above, it is possible to find a solution with the smallest number of master terminals by gradually increasing the number of master terminals until a solution that allows all terminals to participate in the network is found and examining combinations. .
[0063]
Depending on the detection result shown in FIG. 9, a plurality of solutions may be found at the same number of master terminals. In this case, for example, it is desirable to provide a rule such as preferentially selecting a terminal having a small address number as a master terminal so that even when a plurality of solutions are found, it can be narrowed down to one solution.
[0064]
In this embodiment, as shown in FIG. 9, there are two detection results, “detected” and “not detected”. However, the detection frequency such as how many times the detection result is detected by performing the detection operation ten times is measured. Thus, it is conceivable to find a solution to construct a network with a higher detection frequency.
[0065]
Further, in the detection information reception state (b) shown in FIG. 5, the state information notified to the outside by the notification unit 15 is the start information of the switching process in step S25, the result of the switching process in step S27, and the like. It is intended to make it possible to temporarily interrupt data transfer or change routing information due to switching processing in an upper layer such as a transport layer or a network layer.
[0066]
As a result, if the data cannot be sent during the switching process, the data transmission / reception process is temporarily stopped by the upper application, or the routing information is changed according to the result of the switching, and the data is reliably transmitted to the other party. It becomes possible to do. Further, the notification unit 15 can be used to notify the user that switching is being performed using a display panel or the like provided in the terminal.
[0067]
Next, processing in the periodic detection state will be described with reference to FIG. First, the detection unit 12 detects whether there is a communicable terminal (S30), and whether the detection result is the same as the previous detection result stored in the storage unit 13 or not. The control unit 14 determines (S31). When it is determined that they are the same, the state transits to the idle state (a).
[0068]
On the other hand, if it is determined that they are different, the detection information stored in the storage unit 13 is updated based on the current detection result (S32). And it changes to detection information transmission state (d).
[0069]
Next, processing in the detection information transmission state will be described with reference to FIG. First, the communication unit 11 transmits the detection information stored in the storage unit 13 to the communication destination terminal (S40), and the control unit 14 constructs a network based on the detection information stored in the storage unit 13. Is calculated (S41). The optimal solution calculation process is the same as the process in step S23.
[0070]
Next, the control unit 14 compares the communication destination indicated by the optimal solution for network construction with the current communication destination, and determines whether or not switching of the communication destination is necessary (S42). Since the communication destination is the same, when it is not necessary to switch the communication destination, a transition is made to the idle state (a).
[0071]
On the other hand, if the communication destinations need to be switched because the communication destinations are different, the notification unit 15 notifies the outside of starting the communication destination switching process (S43), and the communication unit 11 Is switched (S44). In response to the result of the switching process, the notification unit 15 notifies the result of the switching process to the outside (S45), and the storage unit 13 updates the contents of the stored detection information (S46). Then, it returns to step S40 and repeats the said operation | movement.
[0072]
Through the above processing, the network topology can be changed using the detection information so that the number of master terminals is reduced, so that an increase in power consumption and a reduction in communication speed in the entire network can be suppressed. .
[0073]
In addition, by calculating the optimal solution for network construction, the number of master terminals that can construct the network can be minimized, so that the increase in power consumption and the reduction in communication speed in the entire network can be minimized. it can.
[0074]
In addition, by notifying the start of the switching process and the result to the outside, data is transmitted to the terminal during the switching process by stopping the transmission to the terminal during the switching process or changing the routing information. This can prevent data loss.
[0075]
[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 11 shows a configuration of a communication apparatus according to the communication method of the present invention. The communication apparatus includes a network control block 20 and a flag storage block 26.
[0076]
The network control block 20 includes a control processing unit 21 that controls the system, a detection processing unit 22 that detects communication terminals that can communicate, a storage processing unit 23 that stores detection information, and communication that communicates with other communication terminals. It is the structure provided with the process part 24 and the notification process part 25 which performs notification to the exterior. Each process part 21-25 can process in parallel, respectively. The flag storage block 26 includes a detection information comparison flag, a detection information update flag, a detection information transmission flag, an optimal solution calculation flag, a periodic detection flag, and a switching start notification in order to coordinate the processing units 21 to 25. A flag, a communication destination switching flag, and a switching completion notification flag are stored.
[0077]
Next, the process performed in each process part 21-25 is demonstrated based on FIGS. 12-17. It is assumed that the initial state of the flag stored in the flag storage block 26 is OFF.
[0078]
First, processing performed in the control processing unit 21 will be described with reference to FIG. First, the control processing unit 21 determines whether or not the detection information comparison flag is ON (S100).
[0079]
If it is ON, the contents are compared with the existing detection information (S104), and the detection information comparison flag is turned OFF (S105). Next, if the contents are the same (YES in step S106), the process returns to step S100 as it is, but if the contents are different (NO in step S106), the detection information update flag is turned ON. After (S107), the process returns to step S100.
[0080]
On the other hand, when the detection information comparison flag is OFF in step S100, the control processing unit 21 determines whether or not the optimal solution calculation flag is ON (S101).
[0081]
If it is ON, the optimal solution for network construction is calculated from the detection information (S108), and the optimal solution calculation flag is turned OFF (S109). Next, it is determined whether or not switching of the communication destination is necessary by comparing the calculated communication destination of the optimal solution with the current communication destination (S110). If it is determined that switching of the communication destination is unnecessary because the communication destination is the same, the process directly returns to step S100. On the other hand, if it is determined that the communication destination needs to be switched because the communication destinations are different, the switching start notification flag is turned on (S111), and the process returns to step S100.
[0082]
On the other hand, when the optimal solution calculation flag is OFF in step S101, the control processing unit 21 determines whether or not the interval period measured in advance has elapsed (S102). If it has not yet elapsed, the process directly returns to step S100. On the other hand, if it has elapsed, after turning on the periodic detection flag (S103), the process returns to step S100 to repeat the above operation.
[0083]
Next, processing performed in the detection processing unit 22 will be described with reference to FIG. First, the detection processing unit 22 waits until the periodic detection flag is turned on (S120), and when it is turned on, performs detection processing for detecting a communicable terminal (S121). After completion of the detection process, the periodic detection flag is turned off (S122), and the detection information comparison flag is turned on (S123). Then, it returns to step S120 and repeats the said operation | movement.
[0084]
Next, processing performed in the storage processing unit 23 will be described with reference to FIG. First, the storage processing unit 23 waits until the detection information update flag is turned ON (S130). When the detection information update flag is turned ON, the storage processing unit 23 performs detection information update processing (S131), turns the detection information update flag OFF (S132), and detects. The information transmission flag is turned on (S133). Then, it returns to step S130 and repeats the said operation | movement.
[0085]
Next, processing performed in the communication processing unit 24 will be described with reference to FIG. First, the communication processing unit 24 determines whether or not the detection information transmission flag is ON (S140).
[0086]
In the case of ON, the detection information is transmitted to the communication partner (S144), the detection information transmission flag is turned OFF (S145), and the optimum solution calculation flag is turned ON (S146). Thereafter, the process returns to step S140.
[0087]
On the other hand, when the detection information transmission flag is OFF in step S140, the communication processing unit 24 determines whether or not the communication destination switching flag is ON (S141).
[0088]
If it is ON, the communication destination is switched (S147), the communication destination switch flag is turned OFF (S148), and the switch completion notification flag is turned ON (S149). Thereafter, the process returns to step S140.
[0089]
On the other hand, if the communication destination switching flag is OFF in step S141, the communication processing unit 24 determines whether detection information has been received from the other party (S142). If not received, the process directly returns to step S140. On the other hand, if it is received, after the detection information comparison flag is turned on (S143), the process returns to step S140 and the above operation is repeated.
[0090]
Next, processing performed in the notification processing unit 25 will be described with reference to FIG. First, the notification processing unit 25 determines whether or not the switching start notification flag is ON (S150).
[0091]
If it is ON, the start of the switching process is notified to the outside (S152), the switching start notification flag is turned OFF (S153), and the communication destination switching flag is turned ON (S154). Thereafter, the process returns to step S150.
[0092]
On the other hand, when the switch start notification flag is OFF in step S150, the notification processing unit 25 determines whether or not the switch completion notification flag is ON (S151).
[0093]
If it is ON, the completion of the switching process is notified to the outside (S155), the switching completion notification flag is turned OFF (S156), and the detection information update flag is turned ON (S157). Then, it returns to step S150 and repeats the said operation | movement.
[0094]
In the above-described embodiment, a wireless network that performs wireless communication has been described. However, the network is configured to include a node that is in a one-to-many link form and can operate in both master mode and slave mode. If so, the present invention can be applied to a wired network that performs wired communication.
[0095]
The present invention can also execute the processing by recording the above-described processing steps on a computer-readable recording medium recording a program to be executed by a computer. Thereby, the recording medium which recorded the program for performing the said process step can be carried and provided freely.
[0096]
As this recording medium, a program medium such as a memory (not shown) such as a ROM may be used for processing by the microcomputer, or a program reader is provided as an external storage device (not shown). It may be a program medium that can be read by inserting a recording medium therein.
[0097]
In any case, the stored program is preferably configured to be accessed and executed by the microprocessor. Furthermore, it is preferable that the program is read out, and the read program is downloaded to a program storage area of the microcomputer and the program is executed. It is assumed that this download program is stored in advance in the main unit.
[0098]
The program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, a CD-ROM / MO / MD / DVD, or the like. Optical discs, IC cards (including memory cards) / optical cards, etc., semiconductors such as mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), flash ROM, etc. There is a recording medium that carries a fixed program including a memory.
[0099]
In addition, if the system configuration is capable of connecting to a communication network including the Internet, the recording medium is preferably a recording medium that fluidly carries the program so as to download the program from the communication network.
[0100]
Further, when the program is downloaded from the communication network as described above, it is preferable that the download program is stored in the main device in advance or installed from another recording medium.
[0101]
Finally, the above embodiment does not limit the scope of the present invention, and various modifications are possible within the scope of the present invention. For example, the following embodiments can be configured.
[0102]
That is, the communication device according to the present invention stores communication means capable of both master mode and slave mode operations, detection means for detecting the presence of other communication devices, and detection information obtained from the detection means and the like. Storage means, and determination means for selecting a communication destination using detection information stored in the storage means so that the number of dual communication devices operating in the master mode in the network is reduced.
[0103]
According to the above configuration, the detection information obtained from the communication device is obtained by the detection means and stored by the storage means. Further, the detection information obtained by adding the detection information of the other communication apparatus is stored in the storage means by notifying each other of the detection information obtained from the communication apparatus by the communication means. Furthermore, the communication destination is selected so that the number of communication devices operating in the master mode connected to the network is reduced based on the detection information stored by the determination means. If the selected communication destination is different from the current communication destination, the communication destination is changed by the communication means.
[0104]
Therefore, the communication devices connected to the network can be reconfigured so that the number of communication devices operating in the master mode connected to the network individually is reduced. By reducing the number of communication devices that operate in the master mode in the network, it is possible to suppress power consumption of the entire network and prevent a reduction in processing speed. As a result, a communication device with low power consumption and high processing speed can be provided.
[0105]
Furthermore, the communication apparatus according to the present invention has a configuration including notification means for notifying state information to the outside in the above configuration. According to said structure, a notification means notifies the state of a communication apparatus as status information with respect to the other apparatus in the terminal carrying the said communication apparatus. Therefore, it is possible to notify the communication destination switching start or switching completion, and as a result, it is possible to pause data transmission or change routing information during the switching process.
[0106]
In addition, the communication method according to the present invention is obtained from a detection step for detecting the presence of a communication device, a communication step for performing communication processing capable of both master mode and slave mode operations, the detection step, and the communication step. A storage step of storing the detected information, a determination step of selecting a communication destination using the detection information so that the number of dual communication systems operating in the master mode in the network is reduced, and the selected communication destination This is a method including a switching step of switching the communication destination when the current communication destination is different.
[0107]
According to said method, the detection information obtained from a self-communication apparatus by a detection step is acquired, and it memorize | stores by a memory | storage step. Further, the detection information stored in each other is notified in the communication step, and the detection information including the detection information of the other communication device obtained in this way is stored in the storage step. In the determination step for selecting the communication destination, the communication destination is selected based on the stored detection information so that the number of dual communication systems operating in the master mode in the network is reduced. Make changes.
[0108]
Therefore, it is possible to suppress power consumption of the entire network and prevent a reduction in processing speed. As a result, a communication system with low power consumption and high processing speed can be provided.
[0109]
Furthermore, the communication method according to the present invention is a method further comprising a notifying step of notifying state information to the outside in the above method. According to the above method, the notifying step notifies the status of the communication system as status information to other devices in the system including the communication device. Therefore, it is possible to notify the communication destination switching start or switching completion, and as a result, it is possible to pause data transmission or change routing information during the switching process.
[0110]
A program according to the present invention is for causing a computer to realize the communication method. Thereby, the computer which implements this invention can provide the program which implement | achieves the communication apparatus which can suppress consumption of electric power, and can prevent the fall of a processing speed, and a communication system.
[0111]
A recording medium according to the present invention records the above program. Thereby, a recording medium for causing a computer to execute the program can be provided.
[0112]
【The invention's effect】
As described above, the network restructuring method of the present invention includes a detection step of detecting a node to which each node can link, a creation step of creating detection information including a detection result of each node by the detection step, and the creation A selection step for selecting the master node and a construction step for constructing a small network including the node selected by the selection step so that the number of the master nodes is reduced using the detection information created in the step. It is the method of including.
[0113]
As a result, it becomes clear from the detection information created by the creation step that each node included in the network can be linked to which node, so the network topology is changed so that the number of master nodes is reduced. Can do. Therefore, since the number of master nodes is reduced, there is an effect of suppressing an increase in power consumption in the entire network and a reduction in communication speed.
[0114]
The selection step includes a first search step for searching for one node to which all the nodes can be linked, and if no corresponding node can be found in the first search step, all the nodes are included in the combination of the nodes. A combination of the nodes that can be linked to the node, a second search step of searching for a node that can be linked to at least two nodes in the combination of the nodes, and a node that corresponds in the second search step Cannot be found, increase the number of nodes in the combination of the nodes and repeat the second search step, and the corresponding node in the first search step or the corresponding node in the second search step. And a determination step of determining a combination as the master node.
[0115]
In this case, since the number of master nodes that can construct a network can be minimized, there is an effect of suppressing the increase in power consumption and the reduction in communication speed to the maximum in the entire network.
[0116]
Furthermore, as described above, the network restructuring method of the present invention is a method in which, in the above method, the construction step includes a notification step of notifying other nodes that the node is switching the link destination. is there.
[0117]
Thus, by stopping transmission to the node being switched or changing the routing information, there is an effect of preventing data loss due to data being transmitted to the node being switched.
[0118]
Further, as described above, the node of the present invention constitutes a network including a detecting unit that detects a linkable node, a detection result of the own node acquired by the detecting unit, and a plurality of the small networks. Storage means for storing detection information including detection results of each node, communication means for communicating the detection information with the outside, and using the detection information, so that the number of master nodes in the network is reduced. Master selection means for selecting the master node and construction means for selecting a mode of the own node based on the selection of the master selection means and constructing a small network by selecting a link destination node It is a configuration.
[0119]
As a result, it becomes clear from the detection information stored in the storage means to which node each node included in the network can be linked, so that the network topology is changed so that the number of master nodes is reduced. Can do. In this case, since the number of master nodes is reduced, there is an effect of suppressing an increase in power consumption in the entire network and a reduction in communication speed.
[0120]
The master selection means includes a first search means for searching for one node to which all the nodes can be linked, and if the corresponding node cannot be found by the first search means, all the nodes are included in the combination of the nodes. Corresponding in a second search means for searching for a combination of the nodes that can be linked to any one of the nodes, a node that can be linked to at least two nodes in the combination of the nodes, and a second search means If the node to be found cannot be found, it repeats the second search means by increasing the number of nodes in the combination of the nodes, and the corresponding node in the first search means, or the corresponding in the second search means A determining unit that determines a combination of nodes as the master node may be provided.
[0121]
In this case, since the number of master nodes that can construct a network can be minimized, there is an effect of suppressing the increase in power consumption and the reduction in communication speed to the maximum in the entire network. Further, when other nodes have the same configuration, the master node determined by the determining means is common to each node. Therefore, there is a special node for determining the master node and changing the network topology. There is an effect that becomes unnecessary.
[0122]
Furthermore, as described above, the node according to the present invention has a configuration in which, in the above configuration, the construction unit includes a notification unit that notifies the outside of execution of a switching process for linking with the selected link destination node. is there.
[0123]
As a result, the execution of the link destination switching process can be notified to other nodes, so that the other node can stop the transmission to its own node or change the routing information. There is an effect of preventing data loss due to data being transmitted to the own node.
[0124]
The link destination changing method of the present invention includes a detection step of detecting a linkable node, and detection information including a detection result of each node acquired by the node constituting the network including the plurality of small networks by the detection step. A reception step for receiving the received detection information, an update step for updating the received detection information with the detection result of the own node acquired by the detection step, and a transmission step for transmitting the detection information updated by the update step to the outside And using the detection information updated in the updating step, a first selection step for selecting the master node so that the number of the master nodes in the network is reduced, and selection in the first selection step. Based on this, the second selection step for selecting the mode of the own node and for selecting the link destination node is performed. If, in the case where the destination and the current link destination selected by the second selection step are different, the method comprising the switching step for switching destination.
[0125]
As a result, it becomes clear from the detection information updated in the updating step that each node included in the network can be linked to which node, so that the network topology is changed so that the number of master nodes is reduced. Can do. In this case, since the number of master nodes is reduced, there is an effect of suppressing an increase in power consumption in the entire network and a reduction in communication speed.
[0126]
It should be noted that each step in the network reconstruction method can be executed on a computer by a network reconstruction program. Similarly, each step in the link destination changing method can be executed on a computer by a link destination changing program.
[0127]
Furthermore, the network reconstruction program or the link destination change program can be executed on an arbitrary computer by storing the network reconstruction program or the link destination change program in a computer-readable recording medium.
[Brief description of the drawings]
FIG. 1A is a block diagram illustrating an example of a network configuration, and FIG. 1B is a block diagram illustrating a case where a new terminal participates in the network of FIG. FIG. 4C is a block diagram showing a network in which the network of FIG. 4B is reconfigured according to the present invention.
FIG. 2 is a block diagram showing a schematic configuration of a terminal used in a network according to an embodiment of the present invention.
FIG. 3 is a state transition diagram showing transition of operation states of the terminal.
FIG. 4 is a flowchart showing a processing operation when the terminal is in an idle state.
FIG. 5 is a flowchart showing a processing operation when the terminal is in a detection information reception state.
FIG. 6 is a flowchart showing a processing operation when the terminal is in a periodic detection state.
FIG. 7 is a flowchart showing a processing operation when the terminal is in a detection information transmission state.
FIG. 8 is a block diagram illustrating a configuration example of a network used in the present embodiment.
FIG. 9 is a diagram showing detection information, which is a detection result of each terminal, in a table format in the network.
FIG. 10 is a diagram showing, in a tabular form, results obtained by using the detection information in order to obtain the minimum master terminal and its terminal name that enable all terminals to communicate on the network. (A) shows the case where there is one master terminal, and (b) in the figure shows the case where there are two master terminals.
FIG. 11 is a block diagram showing network control performed in a terminal used for a network according to another embodiment of the present invention.
FIG. 12 is a flowchart showing a processing operation of a control processing unit performed in the terminal.
FIG. 13 is a flowchart showing a processing operation of a detection processing unit performed in the terminal.
FIG. 14 is a flowchart showing a processing operation of a storage processing unit performed in the terminal.
FIG. 15 is a flowchart showing a processing operation of a communication processing unit performed in the terminal.
FIG. 16 is a flowchart showing a processing operation of a notification processing unit performed in the terminal.
FIG. 17 is a diagram illustrating another example of detection information in a table format.
FIGS. 18A and 18B are block diagrams showing the difficulty of network construction due to the radio wave arrival distance.
FIGS. 19A and 19B are block diagrams showing the difficulty of network construction due to obstacles.
[Explanation of symbols]
1-7,10 terminal (node)
11 Communication unit (communication means)
12 Detection unit (detection means)
13 Storage unit (storage means)
14 Control unit (master selection means, construction means)
15 Notification section (notification means)
21 Control processing unit (master selection means, construction means)
22 Detection processing unit (detection means)
23 Storage processing unit (storage means)
24 Communication processing unit (communication means)
25 Notification processing unit (notification means)
M Master terminal (master node)
S Slave terminal (slave node)

Claims (14)

A network restructuring method for reconstructing a network including a plurality of small networks linked to one or more nodes operating in a slave mode with respect to a node operating in a master mode,
Each node, a detection step of detecting a linkable node to the node,
Each node collects detection results indicating the linkable nodes in each node by communicating with the nodes detected in the detection step, and whether or not each node can be linked with respect to all the nodes included in each detection result. A creation step for creating detection information indicating
Using detection information created by said creating step, all nodes can join the network, and, as the number of nodes operating in the master mode is to decrease or minimize the nodes operating in the master mode And a selection step of selecting the network.   The selection step includes
  Using the detection information, a first search step of searching n nodes operating in the master mode so that all nodes can participate in the network;
  A second search step of searching for n + 1 nodes operating in the master mode so that all nodes can participate in the network if the corresponding n nodes cannot be searched in the first search step;
  A determination step of determining the node searched in the first search step or the second search step as a node operating in the master mode;
  2. The method according to claim 1, further comprising: a repetition step of repeating the second search step by setting the number of search nodes n + 1 as n when the corresponding n + 1 nodes cannot be searched in the second search step. Network reconstruction method.   The selection step includes
  A first search step of searching for one node to which all the nodes can be linked using the detection information;
  If one corresponding node cannot be searched in the first search step, the number of search nodes to be searched as a node operating in the master mode is increased to 2, and all nodes can be linked to one of the search nodes. And a second search step for searching for two nodes such that all nodes can join the network via nodes that are linkable to both search nodes. 2. The network reconstruction method according to 1.   The repeating step includes
  If the corresponding node cannot be searched in the second search step, the number of search nodes is increased, all the nodes can be linked to any one of the search nodes, and at least two or more of the search nodes The network reconstructing method according to claim 2, wherein the second search step of searching for nodes is repeated so that all nodes can participate in the network via nodes that can be linked to the network.   5. The network restructuring method according to claim 1, further comprising a construction step in which a node selected in the selection step operates in a master mode to construct a small network.   6. The network construction method according to claim 5, wherein the construction step includes a switching step in which each node switches a link destination in accordance with the node selected in the selection step.   The network reconstructing method according to claim 6, wherein the constructing step includes a notifying step of notifying another node that the node is switching a link destination.   A node that can construct a small network in which one or more nodes operating in the slave mode are linked to a node operating in the master mode, and can operate in either the master mode or the slave mode. Node
  Detecting means for detecting a node linkable to the node;
  Communication means for receiving a detection result indicating the linkable node in each node by communicating with the node detected by the detection means;
  Whether each node can be linked with respect to all nodes included in each detection result created from the detection result of the own node obtained from the detection means and the detection result of other nodes obtained via the communication means Storage means for storing detection information indicating
  Master selection that uses the detection information to select nodes that operate in the master mode so that all nodes can participate in the network and the number of nodes that operate in the master mode is reduced or minimized. A node comprising: means.   The master selection means includes
  Execute a first search process for searching for one node that can be linked to all nodes,
  If one corresponding node cannot be searched in the first search process, the number of search nodes to be searched as nodes operating in the master mode is increased to 2, and all nodes are linked to one of the search nodes. Performing a second search process for searching for two nodes so that all nodes can join the network via nodes that are capable of being linked to both search nodes;
  A master determination process for determining the node searched in the first search process or the second search process as a node operating in the master mode;
  If the corresponding two nodes cannot be searched in the second search process, the number of search nodes is increased and the second search process is repeated so as to search for a node where all the nodes can participate in the network. The node according to claim 8.   The master selection means includes
  If the corresponding two nodes cannot be searched in the second search process, the number of search nodes is increased so that all nodes can be linked to one of the search nodes, and at least two of the search nodes The node according to claim 9, wherein the second search process is repeated so as to search for a node that allows all nodes to participate in the network via nodes that can be linked as described above.   The system further comprises: a construction unit that constructs a small network by selecting a mode of the own node based on selection of the master selection unit, or selecting a mode and selecting a link destination node. The node according to any one of 8 to 10.   The node according to claim 11, wherein the construction unit includes a notification unit that notifies the outside of execution of a switching process for linking with a selected link destination node.   A network reconstruction program that causes a computer to execute each step in the network reconstruction method according to any one of claims 1 to 7.   14. A computer-readable recording medium on which the network reconstruction program according to claim 13 is recorded.

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